So the key to the whole test result is in the wording where they say: "Test is terminated when... GPS unit displays a Low Battery Power message".
Personally, I dispute that that message is really a low battery power message, but that's what they're using as their loophole.
Now, on that note, I have a great idea for a new invention (because that's the sort of genius I am, just like Frankie)...
It's a device that you install in cars and it disables the fuel warning light (using amazing new wire snips that I've invented).
So I will do a test, driving the car until either it stops going or the fuel light comes on.
First I'll do the test without my new genius invention installed. I'll stop when the fuel light comes on.
Then, I'll do the test with my invention; let's call it CARRRERRISER!; installed. The test stops when the car stops going.
This test will prove that CARRRERRISER! gives many cars 8 times more travel per tank of fuel.
(NB. CARRRERRISER! does not give some cars 8 times more travel, your milage may vary. For instance, in Australia you may use Kms.)
....
PROFIT!!!!
EDIT: Hmm, now all I need to do is make some Apple-esque ad videos with smooth music in the background, and some guys sitting on stools talking about how fuel lights are such a worldwide problem, and ideally some pretty girls demonstrating my product in action! I'll be a hundred-aire in no time!